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Geometry - Triangle

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dell2: Senior | Next Rank: 100 Posts; Posts: 36; Joined: Thu Jun 02, 2011 10:28 am

by dell2 » Thu Jun 23, 2011 9:41 am

Triangle A has one side of length x. If âˆš(x8) = 81, what is the perimeter of Triangle A?

1) Triangle A has sides whose lengths are consecutive integers
2) Triangle A is NOT a right triangle

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Source: Beat The GMAT — Problem Solving | Thu Jun 23, 2011 9:41 am

Frankenstein: Legendary Member; Posts: 1448; Joined: Tue May 17, 2011 9:55 amFollowed by: 53 members; Location: India; Thanked: 375 times

by Frankenstein » Thu Jun 23, 2011 9:49 am

Hi,
If you meant sqrt(x^8) = 81, then x^4 =81. So, x=3
From(1):
Sides of the triangle can be 2,3,4 or 3,4,5
Not sufficient
From(2):No info. about other sides
Not sufficient

Both(1)&(2):
3,4,5forms a right triangle. So, sides of 2,3,4 is the required triangle.
Sufficient

Hence C

Cheers!

Things are not what they appear to be... nor are they otherwise

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Sajal: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Tue Jul 31, 2012 12:30 pm

by Sajal » Tue Jul 31, 2012 12:34 pm

Why cant the sides be 1,2,3 for option (A)...
and then for A and B together, why are 2,3,4, the only value considered, why not 1,2,3?

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eagleeye: Legendary Member; Posts: 520; Joined: Sat Apr 28, 2012 9:12 pmFollowed by: 49 members; Thanked: 339 times; GMAT Score:770

by eagleeye » Tue Jul 31, 2012 1:55 pm

Sajal wrote:Why cant the sides be 1,2,3 for option (A)...
and then for A and B together, why are 2,3,4, the only value considered, why not 1,2,3?

1,2,3 can never be the sides of a triangle because 1+2=3, and in a triangle, sum of any two sides must always be greater than the third side. If sum of two sides equal the third, it is a straight line and not a triangle.

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